Mutations in PTEN-induced kinase 1 (PINK1) are associated with autosomal recessive parkinsonism. Early studies have uniformly shown a neuroprotective role for PINK1, indicating that studying this familial form of Parkinson's Disease (PD) may offer valuable insights into potential therapeutic strategies. Dysregulation of mitochondria and autophagy are each centrally implicated in toxin, genetic and environmental approaches to modeling PD. Using knockdown and targeted expression systems, we identified a set of mitochondrial, autophagic and neurite-stabilizing functions downstream of PINK1. Using differentiated neuronal cell lines and primary neurons harvested from control and PINK1 knockout mice, we will now determine mechanisms by which PINK1 protects in toxin and genetic PD models, focusing on: 1) the role of subcellular localization in PINK1 regulation of mitochondrial and neurite stability, 2) the effects of PD-linked mutations on mechanisms that regulate these two facets of PINK1 neuroprotection, and 3) continued characterization of potential PINK1 pathway mediators, using candidate and nonbiased proteomic approaches. Achieving the goals of this project to obtain a better understanding of PINK1 regulation of autophagy and mitochondria will provide insight into new therapeutic strategies to reduce neuronal dysfunction in PD.